For real this time. A mistake on the last commit like this meant models
were still spuriously instantiated.
Now that the completion model is reused, the layoutChanged signal needs
to be forwarded through, otherwise the view will not update.
Instead set this on inidividual categories, as that is where it actually
gets used. This makes it easier for SqlCompletionCategory to reuse a
prepared query (as it gets the filter field names in its constructor).
Instead of add_list and add_sqltable, the completion model now supports
add_category, and callees either pass in a SqlCategory or ListCategory. This
makes unit testing much easier.
This also folds CompletionFilterModel into the ListCategory class.
Now all completion models are of a single type called CompletionModel.
This model combines one or more categories. A category can either be a
ListCategory or a SqlCategory.
This simplifies the API, and will allow the use of models that combine simple
list-based and sql sources. This is important for two reasons:
- Adding searchengines to url completion
- Using an on-disk sqlite database for history, while keeping bookmarks and
quickmars as text files.
